Constant voltage generator



March 17, 1936. F. F. HUTCHINSON 2,034,470

CONSTANT VOLTAGE GENERATOR Filed April 2, 1935 NEY.

Patented Mar; 17, 1936 [UNITED "STATES PATENT OFFICE 2,034,476 CONSTANT VOLTAGE emu Fenton F. Hutchinson, San Francisco; Calif. Application April 2, 1935, Serial No. 14,230

8 claims; (Cl. 171-223) V eflicacious use of electricalgenerating machines consists of regulation of voltage under variable a standing with respect to the use of alternators, while it does not, altho present, appreciably enter into the efficiency of direct current generrating machines. The issue has in the past been dodged, rather thansolved, by the expedient use, in generating plants, of machines of large capacities which are seldom called upon to deliver more than sixty percent of their rated output.

InlsmallPportable alternators where the generation of the greatest amount of current is desirable-from the smallest machine possible,"control of the potential has not heretofore been made possible without the use of auxiliary equipment thereby increasing cost and weight. A

A still further object of the invention is to provide a constant voltage generator which is characterized by the maintenance of substantial- 1y e t phase relationship between current and 40 volt e under inductive loads thereby producing substantially unity power facto Another object of the invention is 'to provide means for distributing the field'and' armature flux to reduce distortion to a minimum.

A still further object of the invention. is to provide a novel method of maintaining a constant potential on direct and alternating current generating machines under all conditions of variance in power loads.

Other objects of the invention, together with 7 some of the advantageous features thereof, will appear from the following description of the preferred embodiment thereof. which is disclosed in the accompanying drawing. While the pre- 6 ferred embodiment of myinvention is illustrated as the invention, as defined power loads. This factor is particularly out- It is a primary object of invention to particularly adaptable for workin the mobile in the drawing, it is to be understood that I am not to be limited to the embodiment shown, in the appended claims, may be embodied in a plurality and variety of fdrms. 5

Referring to the drawing: The accompanying drawing is a diagrammati view of an embodiment of the invention with electrical circuits diagrammatically illustrated.

In accordance with the invention, I-provide a 20 conventional armature H which conveniently may carry two separate windings for producing both alternating and direct current or which, if desired, may carry a single winding, as shown, tapped at points 180 apart for taking off the 5 altemating current at such points. The armature is supported between a pair of diametrically opposed field poles l2 and I3 having arcuate bases, as shown, and upon which I preferably arrange three separate and distinct windings or 30 field coils ll, l6, and H. The field coils l4 and I1 are connected by suitable conductors and brushes to a pair of commutators l8 and I 9 as well as to load circuitsthrough a suitable three pole, double throw switch 20. A conductor 35 ring 2| also is provided in .thegenerator. Field coils i! are made of high resistance to current flow while field coils I4 and I 6 are of relatively low resistance to current flow. Field coils l4 anddi are so arranged on the field poles I2 40 J and I; that they produce magnetic lines of force in opposite directions when current flows through the coils in one direction only.

, commutator I8 is designed so as to take the alternating current produced in the armature winding and rectify the current so as to move the same throughan electrical circuit in one continuous direction. commutator l9 comprises a pair of segments insulated from one another and is so designed as to take the alternating current produced in the armature winding and to directthis current alternately through two separate and individual electrical circuits or, in other words, is so designed as to cause the alter- 'nating current. from the armature recurrently to '55 In its preferred form, the constant voltage 16 flow through one circuit for a period of time equivalent to the completion of one half of an alternating current cycle and then throughanother circuit for a corresponding period 'of time.

As illustrated in the drawing, field coils H are connected in shunt to rectifying commutator l8 by means of brushes 22 and conductors 23 and 24. Conductors 26 and 21 are provided for connecting the brushes 22 of the commutator l8 to the contacts 52 and 53 respectively of the switch 20. Field coils l6 are connected by means of conductors 28, 29, and 30 to difierent contacts j 54 and 56 oi the same s itch, while conductors 3| and 32 leading to direct current load are connected across contacts 51 and BI respectively of the switch 20.

With switch contacts ii to 51 inclusive closed,

.the' machine can be operated as a direct current 7 generator and the device becomes a standard compound wound generator employing field windings l6 and H, the circuits being arranged so that field coils I! are connected in'parallel with the armature and load circuit while the field coils ii are connected in series with the armature and the load circuit, as illustrated. It is apparent that field coils I4 together with commutator l9/and collector ring 2! are not used when the machine is operated as a direct current generator.

In order to place the field coils 14 in the armature and alternating current load circuit, a conductor .33 is providedfor connecting one of th e fields l4 to a switch contact 58 leading to one side of the distributing circuit, a conductor 34 lector ring by means of a suitable brush M and vfed directly to the other side of the distributing alternating current circuit by means of a conductor, 42 connecting the brush 4! and a switch cont'actill. Conductors 43 and 44 lead from the alternating current load to the switchcont s 58 and 60 respectively. The brushes 35 a d 38 of commutator HI are so placed that the segment of the commutator l9 to which the winding of the armature is connected by means of the conductor spans, in one of its positions, both brushes by approximately one-half 0t their width and, accordingly, the flow of current in the arma- ,ture' winding when thesegment is in this position, will be practically zero, since the current tends to fiow through fields I4 and IS in. the same direction, and these fields, being opposed to eachother, set up. a neutral effect.-

With switch'contacts 54 to inclusive closed, the machine is operable'as an alternator with 2 field windings l4, lfi and. It all being utilized;- altho windings I! are. used merely to bringll ithe desired potential at no load. Upon inspection of the drawing it will be observed that current flowing mm the collector ring 2| to' the distributing alternating current circuit must return first thru field coils I 6 on one-half of the cycle and-then thru field coils H on-the other half of the "cycle. Bearing in mindthat field coils i4 and I6 are so arranged as-to produce magneticr lines of force in opposite directions when our- In view of the circuit arrangements as hereinabove described and as illustrated in the draw- I 1 of predetermined -value at noload, and mea maintaining the voltage at said .predete talue under -'load variations; said last named means comprising a collector ring connected to one 7 rent flows therethrough in one direction only, it will be apparent that if current is caused to flow thru coils i6 onone-half of the cycle so as to produce magnetic lines of force moving in a given direction, the current flowing thru 5 coils Ii upon the return of the half cycle, altho flowing in the opposite direction, will produce magnetic lines of force moving in the same direction as they did when the current fiowed thru coils IS on the first half of the cycle. v

ings the voltage will not be affected regardless of the variations in inductive and resistance loads placed on the machine. Moreover since the field 15 strength is in proportion to the load carried and inasmuch as the field strength is reduced to practically zero at every half cycle by reason of the position of the brushes 36 and 38 on the commutator IS, the current and voltage arekept in 20 exact phase relationship under all inductive I loads, thereby producing substantially unity power factor. Furthermore, since the field strength varies from maximum to. practically zero every half cycle, the field and armature 2 5 magnetic flux are more evenly distributed and. distortion thereioreis reduced to a minimum.

1 It is to be understood that the appended claims are to be accorded a range of equivalents com-v mensurate with the scope of the prior art.

pair of field poles, an armature having a winding thereon, an alternating current circuit, a collector ring connected to-one side of said circuit and to said winding,'and two pairs of field coils wound 3 upon each of said poles and connected to the other side of said circuit and to saidv winding; one pair of said pairs of coils being wound so that current flowing therethroughin one direction will produce magnetic lines of force moving in a given direction, and the other pair of said pairs of cells being wound so that current flowing therethrough in the opposite direction will producemagnetic lines of iorce moving in said given directioni 2. A constant voltage alternator for feeding an 4 alternating current load circuit; said alternator comprising a pair of field poles, an armature having a winding thereon, means for creating a magnetic flux of predetermined value upon said field poles whereby the alternator produces a voltage of predetermined value at no load, and means for maintaining the voltage'at said predetermined value under load variations said last named means including a collector ring connected to one side of said load circuit and to said winding, and two pairs of field coils wound upon said poles and connected to the other side of said circuit and to said winding; one of said. pairs oi! coils being wound so'that current flowing therethrough in one i 9 1. A constant. voltage generator comprising a T direction will produce magnetic lines of force moving in a given direction and the other of said pairs of coils being wound so that current flowing therethrough in the opposite direction will producer magnetic lines of force moving in said given 11- 65 rection. t r

3. A constant voltage alternator for-feeding an alternating current load circuit; said alternator comprising a pair of field poles, an armature hav-- ing a winding thereon, means for creating a magnetic flux of predetermined value upon saidfield poleswhereby the alternator-produces a voltage for ned the other side or said circuit and to said armature,

and means for causing current to fiow in one direction thru one pair of said coils during one-half of an alternating current cycle and to fiow in the opposite direction through the other of said pairs of coilsduring the other half of said alternating current cycle.

4. A constant voltage alternator for feeding an alternating current load circuit; said alternator comprising a pair of field poles, an armature having a winding thereon, means for creating a magnectic fiux of predetermined value on said field poles whereby the alternator produces a voltage of predetermined value at no load, and means for maintaining the voltage at said predetermined value under variations of load; said last named means comprising a collector ring connected to one side of said load circuit and to said winding, two pairs of field coils wound upon said field poles and connected to the other side of said load circuit and to said armature, and a commutator in the field coils circuits for directing the current in one direction through one pair of coils during onehalf of an alternating current cycle and in the opposite direction through the other pair of coils during the other half 'of the alternating current cycle; said commutator comprising a pair of segments insulated from one another, one segment being connected to said armature winding.

5. A constant voltage alternator for feeding an alternating current load circuit; said alternator comprising a pair of field poles, an armature having a winding thereon, a first commutator electrically connected to-said winding, 9. pair of field coils of relatively high resistance to current flow wound on said poles and connected in shunt to said first commutator; said field coils creating a magnetic flux on said field poles whereby the alternator produces a voltage of predetermined value at no load, and means for maintainingthe voltage at said predetermined value under load variations; said means comprising a collector ring connected to one side oi said circuit and tosaid winding, two pairs of field coils of relatively low resistance to current flow wound on said poles and connected to the other side of said circuit and to said armature, and a second commutator having a pair of segments insulated from each other with one segment connected to said winding; said commutator being interposed in a circuit including said winding and said one commutator segment together with one pair of said field coils for energization during one-half of an alternating current cycle, and being interposed in another circuit including said winding and saidone commutator segment together with the other pair of said field coils for energization during the other half of the alternating current cycle. l p

6. A constant voltage generator comprising a pair of field poles, an armature having a winding thereon, a first commutator electrically connected to said winding, a pair of brushes spaced 180 apart on said first commutator, a second commutator having a pair of segments insulated from each other, a conductor leading from said 5 winding to one segment of said second commutator, a pair 01' brushes spaced 180 apart on said second commutator, a first pair of field coils of relatively high resistance to current fiow wound on said field poles and connected in shunt with said armature, a second pair or field coils of relatively low resistance to current fiow wound on said field poles and connected in series with said armature through said brushes, and a third pair or field coils of relatively low resistance to cur- 5 rent flow wound upon said field poles and connected in series with said armature through said brushes.

7. In a constant voltage alternator for feeding an alternating current load circuit, a pair of field poles, an armature having a winding thereon, means for creating a magnetic flux of predetermined value upon said field poles whereby the alternator produces a voltage of predetermined value at noload, and means for maintaining the voltage at said predetermined value under load variations; said means comprising a'commutator having a pair of segments insulated fromeach other, a pair of brushes spaced 180 apart on said commutator, a conductor leading from said winding to one segment of said commutator, and two pairs of fieltiv goils of relatively low resistance to current flow und upon said field poles; said field coils being connected to said commutator through said brushes by separate circuits so that current is caused to fiow alternately through one circuit including one pair of field coils during one-half of an alternating current cycle, and through another circuit including the other pair of field coils during the other half of the alter- 40 nating current cycle.

8. A constant voltage generator comprising a pair of field poles, an armature having a winding thereon, a direct current circuit, an alternating current circuit, a first commutator electrically connected to said winding, a pair of brushes spaced 180 apart on said first commutator, a second commutator having a pair of segments insulated from each other, a conductor leading from said winding to one segment of said second commutator, a pair of brushes spaced 180 apart on said second commutator, a first pair of field coils of relatively high resistance to current fiow wound on said field poles and connected in shunt to said brushes of said first commutator, a second pair of field coils of relatively low resistance to current fiow wound on said field poles and connected in series with said armature and said direct 

